JPH02167803A - Separation method of hf by phase - Google Patents

Abstract

PURPOSE: To substantially completely separate HF from organic components by condensing a mixture to be treated in a condition of prescribed pressure and temp. respectively, separating the mixture to the bottom layer of an organic phase contg. a part of HF and the top layer of an acid phase contg. most part of HF and using phase separation and distillation.

CONSTITUTION: The mixture 1 comprising HF, CF₃CHCl₂ (FC-123) and/or CF₃ CHClF (FC-124) is passed through a cooler 2 in a condition of a temp. from about -80 to about 40°C and a pressure from about 0.10 to about 3.55 MPa. The mixture is sent to separation zones 4 held in the same condition, whereby the organic phase 5 having less than 15 mole % HF is formed as the bottom layer and the acid phase 6 having at least 93 mole % HF is formed at the top thereof. Then, the acid phase 6 is removed from the top in the separation zone 4 and is sent to a multiplate distillation column 10. Distillation is executed in the column 10 in a condition of a temp. from about -4 to about 133°C and a pressure from about 0.10 to about 3.55 MPa to remove basically pure HF11 from the bottom part of the column 10. Meanwhile, a reboiler 12 inputs heat into the column 10 by reevaporating a part of the mixture 1.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides hydrogen fluoride, 2,2-cyclo-1,1,1-trifluoroethane (FC-123) by phase separation.
, and/or 2-chloro-1°1.1.2-tetrafluoroethane (FC-124).

Effective utilization of HF is important from both economic and process operability standpoints. Techniques for separating and recovering HF from fluorocarbon process streams are disclosed in the following patent documents.

US Pat. No. 2,478,362 discloses the use of a continuous separation zone to separate the organic phase from the HF and then recycle it to the reactor feed system.

U.S. Patent No. 3.406.099 describes CF 3 COCF 3 , HF 1CC12F CC
Azeotropic systems useful for separating these materials from mixtures containing one or more of I F2 are disclosed.

U.S. Patent No. 3,873,629 discloses that HF and CI CH
By countercurrent contacting of a gas mixture of F2 with H2SO4,
A continuous process for separating a mixture of HF and CI CHF2 is disclosed.

U.S. Pat. No. 3,947,558 discloses the method of first separating HCI and then cooling it to form an HF-rich layer and an HF-free organic phase. A method for separating HF from reaction products generated by hydrocarbon fluorination is disclosed. This organic phase has 2 carbon atoms
~8 liquid glycol and then the HF-enriched glycol layer is separated from the herocarbon layer.

HF is separated from the glycol by distillation.

US Pat. No. 3,976.447 discloses separating HF from a gas mixture by treating with dry particles of CaCl2, BaCl2 or 5rCI2 and then desorbing the HF.

U.S. Pat. No. 4,209,470 adds a co-solvent and
A method is disclosed for separating HF from a liquid mixture with 1-chloro-1,1-difluoroethane by enriching the HF composition of a liquid inorganic phase in a separation zone. The HF is then separated from the inorganic phase by distillation.

European Patent No. 98.341 describes a separation process for HF and 1-chloro-1,1-difluoroethane that does not require co-solvents, even when the feed stream to the separation zone contains pentafluorobutane. Disclosed. Additionally, the disclosure states that pentafluorobutane contributes to the mutual solubility of HF and 1-chloro-1,1-difluoroethane, thus interfering with the separation process. By avoiding contamination and having good temperature control, the separation is carried out without the use of co-solvents.

A need exists to produce other fluorocarbons useful as refrigerants and blowing agents, or as intermediates in the production of other fluorocarbons useful therein.
This has spurred interest in the manufacturing process of FC-23 and FC-124. These materials are blowing agents, refrigerants, and highly useful fluorocarbon refrigerants 1,1,1.
It is useful as an intermediate in the production of 2-tetrafluoroethane (FC-134a).

FC described in U.S. Patent Application No. 070,826
One method for making -123 and FC-124 involves gas phase hydrofluorination of halogenated alkenes with excess HF. This process uses HF, FC-123, FC-124, tetrachlorethylene, HCl, and 1,2.2-trichloro-1,
Small amounts (less than 5 mole %) of other halogenated products are produced, such as 1-difluoroethane (FC-122) and pentafluoroethane (FC-125). HCI and FC-125 were removed by lli distillation, HF,
FC-123, FC-124, tetrachlorethylene,
This can be easily done by leaving behind a mixture consisting of a small amount (for example less than 5 mole %) of other halogenated products.

One method of separating the reaction mixture proposed earlier by the applicant is under the condition of a controlled HF/FC-123 ratio:
The formation of an HF azeotrope with FC-123 and FC-124 is used.

The present invention provides another method of separation of HF from FC-123 and FC-124 using phase separation and distillation.

The present invention provides pressures in the separation zone of from about 0.10 MPa to about 3
．． Hydrogen fluoride, 2,2-cyclo-
1,1,1-trifluoroethane and/or 2-chloro-1,1,1°2-tetrafluoroethane.
A separation method is provided in which an organic layer containing less than 93 mole % HF is formed as the bottom layer of the separation zone and an acid phase containing 93 mole % or more HF is formed as the top layer of the separation zone.

Substantially 85 mol% or more of FC-123, FC-124
, at least one other organic compound that may be present, and less than 15 mole percent HF is removed from the bottom of the separation zone and subjected to distillation to remove residual HF. . The HF-containing distillate is recovered from the top of the distillation column and recycled to the separation zone to recover additional HF, if necessary. substantially more than 95 mole % HF and less than 7 mole % FC-1
23, FC-124, an acid phase consisting of at least one other organic compound that may be present is removed from the top of the separation zone and the remaining FC-123, FC
-124, subjected to distillation to remove other organic compounds that may be present. The HF-containing distillate is recovered from the top of the distillation column and, if necessary, recycled to the separation zone for the reasons mentioned above. Other organic compounds that may be present include tetrachloroethylene and small amounts of (
(e.g. less than 5 mol %) other halogenated products.

The present invention uses phase separation and distillation to remove H from organic components.
Provides virtually complete separation of F. Further, the present invention provides H
It is based on the discovery that F, FC-123, and FC-124 form an azeotrope that is more volatile than their individual components. The present invention further relates to the formation of these azeotropes in the distillative stripping of nearly complete HF from organic components and the distillative stripping of nearly complete organic components from acid components, thereby producing substantially pure HF. and the ability to separate and recover organic components.

The invention also provides that the proportion of HF in the azeotropic composition (recovered in the distillative stripping of the acid and organic phases) is greater than that present in the organic liquid phase of the two-phase system formed by condensation of the feed mixture. It makes use of the discovery. Similarly, the proportion of organic components in the azeotropic composition is greater than that present for two-phase acid solutions. Thus, recycling the azeotrope to the feed mixture condensation step promotes the overall degree of separation, resulting in complete separation of the HF and organic components from each other.

Although the feed mixture to be treated according to the invention can be obtained from a wide variety of sources, it is advantageous to treat the effluent mixture from the production of FC-123 and FC-124 by reaction of tetrachlorethylene with HF. Note that the products from the reaction are removed or recycled as necessary. The effluent mixture from this reaction is H
F.

FC-123, FC-124, tetrachlorethylene,
HC1, and small amounts of halogenated products such as 1,2,2-trichloro-1,1-difluoroethane (FC-122) and pentafluoroethane (FC-125). Low boiling components such as HCI and FC-125 are usually removed and hydrogen fluoride (HF)
Leaving a mixture consisting essentially of FC-123, FC-124, tetrachloroethylene, and small amounts (less than 5 mole %) of other/% logenated raw material, which can be advantageously treated according to the present invention. .

The inventors have found that two phases are formed under various temperatures and pressures. At atmospheric pressure and =40°C, H
F and FC-123 are basically 98.3 mol% (88,
5% by weight) of HF and 1.7 mol% (11,5% by weight) of FC-123;
8.6 mol% (99.8% by weight) of FC-123 and 1.
Two phases are formed: an organic phase consisting of 4 mol% (0.2% by weight) of HF. At the same temperature and pressure, H
F and FC-124 are basically 84.9 mol% (45,
2% by weight) of HF and 15.1 mol% (54.8% by weight)
of FC-124, and essentially 97.6 mol% (99.6% by weight) of FC-124 and 2
, 4 mol% (0.4% by weight) of HF.

Using this information, the inventors determined that HF, FC-12
3. A mixture containing FC-124 and any other organic compounds is heated in a separation zone from about -80°C to about 40°C;
Preferably at a temperature of about -40°C to about 0°C, about 0.10 MP
a to about 3.55 M P a , preferably about 0.10 M
When subjected to a pressure of Pa to about 1.83 MPa, 15 mol%
An organic phase containing less than 94 mole % HF and an acid phase containing more than 94 mole % HF are formed.

The organic phase is formed at the bottom of the separation zone and consists essentially of less than 15 mol% HF and more than 85 mol% FC-123.
, FC-124, and at least one other organic compound that may be present. The acid phase is formed at the top of the separation zone and contains essentially more than 95 mol% H
F, and less than 7 mol% FC-123, FC-124
, consisting of at least one other organic compound that may be present. The exact amounts of the various components of the organic and acid phases within such ranges will depend on the amounts of these components in the feed mixture and the mutual solubility of the phases under the operating temperatures and pressures.

Hereinafter, preferred embodiments of the present invention will be explained with reference to FIGS. 1 and 2. In Figures 1 and 2, mixture 1 consisting essentially of HF, FC-123, FC-124, and small amounts of other halogenated products is shown to be about -
Temperature from 80°C to about 40'C, about 0.10MPa to about 3
．． Pass through cooler 2 under a pressure of 55 MPa. The cooled mixture 3 is heated to a temperature of about -80°C to about 40°C, about 0.0°C.
It is passed to a separation zone 4 maintained at a pressure of 10 MPa to about 3.55 MPa, where an organic phase 5 containing less than 15 mol % HF and an acid phase containing more than 94 mol % HF are formed. acid phase 6 is removed from the top of separation zone 4;
Passing through a heat exchanger 7 and a pressure regulator 8, the resulting acid phase 9 is sent to a multi-plate distillation column 10. The temperature at the top of the distillation column 10 is preferably about -4°C to about 133°C, more preferably about -4°C to about 97°C, and the pressure is preferably about 0.10 MPa to about 3.55 MPa.

More preferably, it is about 0.10 MPa to about 1.83 MPa. Note that the exact temperature depends on the pressure. Essentially pure HF 11 is removed from the bottom of distillation column 10.

Reboiler 12 provides heat input to the distillation column by re-vaporizing a portion of mixture 11. HF5FC-
123, FC-124, and small amounts of other halogenated products are removed from the top 13 of the distillation column 10;
It is sent to the condenser 14. The resulting mixture 15 is recycled through the cooler 2 to the separation zone 4.

In other embodiments of the invention, organic phase 5 is about -15°C.
A top temperature of ~120<0>C and a temperature of about 0.10 MPa to about 3.55 MPa, preferably about 0.69 MPa to about 1.0 MPa.
It can be sent to a second multi-plate distillation column 16 at a pressure of 83 MPa. A mixture 17 of FC-123, FC-124, and other organic compounds that may be present is added to distillation column 1.
6 or recycled to distillation column 16 through reboiler 18 shown in FIG. Second
The mixture 19 of FC-123, FC-124, and HF shown in the figure is removed from the top of distillation column 16 and condenser 2.
0, the cooled mixture 21 is sent to the cooler 2 for recycling to the separation zone 4. Condenser 20 also provides reflux acid for distillation column 16 .

EXAMPLES In the examples below, compound values are in moles and temperatures are in degrees Celsius. All data were obtained computationally using measured and calculated thermodynamic properties. The numbers at the top of the distillation column relate to FIG. 1 for Table 18 and FIG. 2 for Tables 9-14.

Example 1 A purification system with a separation zone temperature of -40° C. and one multi-plate distillation column is operated as shown in Table 1.

The mole percent of HF in the acid phase is 97.4 and the mole percent of HF in the organic phase is 1.5.

Table 1 Example 2 Table 2 shows the effects of changing the temperature of the separation zone.
3.4 and 5.

HF C-123 C-124 Mol%HF Temperature °C Pressure MPa Table 2 53.65 3g, 27 8.00 1.83 Table 4B, 49 2.09 0.76 94.2 1.83 7.16 38.18 7.24 14.2 1.83 IP 53.84 PC-12338,30 Decoy-1247,79 Temperature "C101 Pressure Pa 1.83 55, LO54,38 39,301,00 g, 23 0.44 1. 83 1.83 0.72 53.11 38J0 0.00 7.79 0.00 1.83 0.10 1.26 1.00 0.44 0.10 54.37 1.00 0.44 0.10 HF C-123 C-124 Mol%HF Temperature °C Pressure MPa 53.84 38.27 8.00 1.83 51.31 1.47 0.59 96, l 1.83 2.33 3B, 80 7.41 5.0 1.83 Table HF C-123 C-124 Mol%HF Temperature °C Pressure MPa 53.84 38.27 8.00 1.83 52.94 0.42 97.4 1.83 0.70 37 .29 7.58 1.5 1.83 HF C-123 C-124 Temperature °C Pressure MPa 93.51 0.10 3.89 1.80 0.78 0.10 97.40 1.80 0.78 0 .10 Table HF C-123 C-124 Mol% HF Temperature °C Pressure MPa 53.05 38.27 8.00 1.83 53.4G O056 0,27 98,5 1,83 0,19 37,71 7 ,73 0,4 1,83 HF C-123 C-124 Temperature °C 132 Pressure MPa 1.83 93.51 3.89 1.80 0.78 (,83 97,40 1,80 0,78 1,83 Example 3 The effects of operating the distillation column at various pressures and temperatures are shown in Tables 6-8.

Table F C-123 C-124 Temperature °C 171 Pressure MPa 3.55 93.51 3.89 1.80 0.78 97.40 1.80 0.78 3.55 Example 4 Multi-plate purification system with two When having a distillation column (Figure 2), it is operated under the conditions shown in Tables 9-14.

1F Ni-123 C-124 Mol%HF M”C Pressure MPa 53.87 311.83 7.80 84.68 56.4B 8.22 53.87
2.59 11.2241.83 2.49
39.34 0.00 2.49 0.5L11.
4g 1.19 10.29 0.00 1.
19 2.4993.9 14.2 40 40 85 5B 431
．． 83 1.83 0.89 0.89 0.8
91.83 1F -123 C-124 Temperature °C Pressure MPa 56.48 2.49 1.19 0.69 0.00 38, +13 7.80 0.69 Table F Di-123 C-124 Mol% IIF Temperature 'CIol Pressure MPa 38.33 53.87 1.83 7.80 59.14 40.42 11.12 1.83 58.48 2.68 53.87 2,59
2.681.58 3g, 84 0.00 1.
5g 0.510.83 10.29 0.0
0 0.83 2.5095.9 5.1 1.83 1.83 0. G9 0.69 0
．． 091F 陀-123 陀-124 Mol 9611F Temperature °C Pressure MPa 53.87 3g, 33 7.80 57.29 5B, 47 0.82 53.88
2.59 0.8239.88 1.02 31
84 0.00 1.02 0.5+10.90
0.57 10.32 0.00 0.57 2
．． 5197.3 1.8 -40 -40 85 5[i
431.83 +, 83 0.89 0.69
0.691F to -123 C-124 Temperature C Pressure MPa 56.4B 1.58 0.83 0.69 0.00 7.78 0.69 1F to -123 C-124 Temperature C Pressure MPa 56.48 1. 02 0.57 0.69 0.00 38.33 7.81 0.69 Table 1F ni-123 陀-124 Mol%HP; HJI”C101 Pressure MPa 38.33 53.87 7.80 1.83 5B , 69 58.47 0.58 0.35 98.4 1.83 1.83 39.42 10.67 0.22 53.8B 2.59 38.84 0.00 0.58 10.32 0.00 0!5 0.4 1.83 0.89 0.09 0.G9 0.22 0.51 2.51 1F ni-122 C-123 TCE" C-124 Mol% IIF Temperature °C Pressure MPa 62.02 0 .34 19.85 14.110 2.92 63.64 0.34 20.54 14.82 3.56 1.83 63.28 0.61 C102 0,24 98,8 1,83 0,38 0, 34 19,92 14,80 3,32 1, B 1.83 62.02 0.00 0.00 0.00 0.00 1.23 C102 0,24 0,38 0,41 0,690,890, 89 1F C-123 C-124 Temperature °C Pressure MPa 56.47 0.58 0.35 0.69 0.00 38!3 7.81 0.69 )IF 63.2ft O,00 to -1
22t 044 1℃-1230, til 19. (i5TCE
” 0.02 14.80 to -1240,2
42,92 Temperature C70104 Pressure MPa O,690,69 Tetrachlorethylene ■Miyu 11F 128.96 陀-123 Mol% IIP Temperature C Pressure MPa 101.40 1.83 69.44 Table 152.09 141.10 10. 94 12111
．． 9B 12.20 10.941!4.95
6.57 7g, 39 0.00 fli, 57
8.9595, G 12゜2 40.00 40.00 85.38 84.05
B4.091.83 1.83 0.09 0
．． G9 0. C940,00 1,83

[Brief explanation of the drawing]

FIG. 1 is a flow diagram illustrating one aspect of the present invention;
FIG. 2 is a flow diagram illustrating a second aspect of the invention. 2... Cooler 4... Separation zone, 7... Heat exchanger, 10.16... Distillation column. IP +41.1Ili F-123G, 57 Temperature "C70,00 Pressure beating a 0.69 0.00 (i9.44 91.88 0.69

Claims (6)

[Claims] (1) Approximately 0.10 MPa to approximately 3.5 in the separation zone
Hydrogen fluoride, 2,2-cyclo-1,
1,1-trifluoroethane, and/or 2-chloro-
A method for separating a mixture containing 1,1,1,2-tetrafluoroethane, wherein the condensation forms an organic layer containing less than 15 mol% HF as the bottom layer of the separation zone, A separation method in which an acid phase containing HF is formed as the top layer of the separation zone. (2) The temperature is about -40°C to about 0°C, and the pressure is about 0.10 MPa to about 1.83 MPa.
The method described in. (3) (a) removing the acid phase from the top of the separation zone; (b) removing the acid phase from step (a) at a temperature of from about -4°C to about 133°C and from about 0.10 MPa to about 3.0°C;
2. The method according to claim 1, further comprising the steps of supplying the HF component from the acid phase to the distillation column at a pressure of 55 MPa, and (c) recovering the HF component of step (b) from the bottom of the distillation column. the method of. 4. The method of claim 3, further comprising the steps of: (4) (d) recovering a distillate containing HF from the top of the distillation column; and (e) recycling the distillate of step (d) to a separation zone. . (5) (a) removing the organic phase from the bottom of the separation zone; (b) subjecting the organic phase from step (a) to a temperature of about -15°C to about 120°C and a pressure of about 0.10 MPa;
and (c) recovering the organic phase of step (b) from the bottom of the distillation column. The method described in Section 1. 6. The method of claim 5, further comprising the steps of: (6) (d) recovering a distillate containing HF from the top of the distillation column; and (e) recycling the distillate of step (d) to a separation zone. .